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Publications 2018



D-A-D-2H-benzo[d][1,2,3]triazole Derivatives as p-type Semiconductors in Organic Field-effect Transistors.

I. Torres-Moya, I. Arrechea-Marcos, C. Tardío, J. R. Carrillo, A. Díaz-Ortiz, J. Teodomiro López-Navarrete, M. C. Ruiz Delgado, P. Prieto, R. Ponce.

RSC Adv.2018, 8, 21879-21888.

DOI: 10.1039/c8ra03246g

A series of Donor–π–Acceptor–π–Donor compounds based on a 2H-benzo[d][1,2,3]triazole core branched with different alkynyl donor groups has been characterized and tested in organic field-effect transistors (OFETs). The electronic and molecular structures were elucidated through optical and vibrational spectroscopy in conjunction with DFT calculations. The results indicate that the planarity of the structure and the good intramolecular charge transfer from the electron-donating to the electron-withdrawing fragments play a critical role in the application of the compounds as semiconductors in OFET devices. The compounds were tested in a top-contact/bottom-gate thin film transistor architecture, and they behave as p-type semiconductors.

Self-Assembled Alkynyl Azoles and Benzoazoles as Colored Optical Waveguides.

I. Torres, R. Martín, A. Díaz-Ortiz, P. Prieto, J. R. Carrillo.

Isr. J. Chem. 2018, 58, 827-836.

DOI: 10.1002/ijch.201800030

Different alkynyl azoles and benzoazoles have been synthesized in good yields by carbon‐carbon coupling reactions. The self‐assembly of some of these compounds by the slow diffusion technique led to well‐defined ribbons and needle‐like aggregates. The X‐ray study of some materials showed that the CH‐π interactions involving the C≡C triple bond and the heteroatoms induce aggregation along with H‐bonds due to the methoxy groups. A fluorescence and confocal optical microscopy study of most of the aggregates indicated optical waveguide behavior with different colors.

Photoinduced Palladium‐Catalyzed Negishi Cross‐Couplings Enabled by the Visible‐Light Absorption of Palladium–Zinc Complexes

I. Abdiaj, L. Huck, J. M. Mateo, M. V. Gomez, A. de la Hoz, A. Díaz-Ortiz, J. Alcázar

Angew. Chem. Int. Ed. 201857, 13231 –13236

A visible-light-induced Negishi cross-coupling is enabled by the activation of a Pd0–Zn complex. With this photocatalytic method, the scope of deactivated aryl halides that can be employed in the Negishi coupling was significantly expanded. NMR experiments conducted in the presence and absence of light confirmed that the formation of the palladium–zinc complex is key for accelerating the oxidative addition step.

Visible‐Light‐Induced Nickel‐Catalyzed Negishi Cross‐Couplings by Exogenous‐Photosensitizer‐Free Photocatalysis

 I. Abdiaj, A. Fontana, M. V. Gómez-Almagro, A. de la Hoz, J. Alcázar

Angew. Chem. Int. Ed., 201847, 8473-8477

The merging of photoredox and transition‐metal catalysis has become one of the most attractive approaches for carbon–carbon bond formation. Such reactions require the use of two organo‐transition‐metal species, one of which acts as a photosensitizer and the other one as a cross‐coupling catalyst. We report herein an exogenous‐photosensitizer‐free photocatalytic process for the formation of carbon–carbon bonds by direct acceleration of the well‐known nickel‐catalyzed Negishi cross‐coupling that is based on the use of two naturally abundant metals. This finding will open new avenues in cross‐coupling chemistry that involve the direct visible‐light absorption of organometallic catalytic complexes.

Pushing nuclear magnetic resonance sensitivity limits with microfluidics and photo-chemically induced dynamic nuclear polarization

Among the methods to enhance the sensitivity of nuclear magnetic resonance (NMR) spectroscopy, small-diameter NMR coils (microcoils) are promising tools to tackle the study of mass-limited samples. Alternatively, hyperpolarization schemes based on dynamic nuclear polarization techniques provide strong signal enhancements of the NMR target samples. Here we present a method to effortlessly perform photo-chemically induced dynamic nuclear polarization in microcoil setups to boost NMR signal detection down to sub-picomole detection limits in a 9.4T system (400 MHz 1H Larmor frequency). This setup is unaffected by current major drawbacks such as the use of high-power light sources to attempt uniform irradiation of the sample, and accumulation of degraded photosensitizer in the detection region. The latter is overcome with flow conditions, which in turn open avenues for complex applications requiring rapid and efficient mixing that are not easily achievable on an NMR tube without resorting to complex hardware.

Illumination of Nanoliter-NMR Spectroscopy Chips for Real-Time Photochemical Reaction Monitoring

M. V. Gómez, A. Juan, F. Jiménez-Márquez, A. de la Hoz, A. Velders

Anal. Chem.201890 (3), pp 1542–1546

We report the use of a small-volume nuclear-magnetic-resonance (NMR)-spectroscopy device with integrated fiber-optics for the real-time detection of UV–vis-light-assisted chemical reactions. An optical fiber is used to guide the light from LEDs or a laser diode positioned safely outside the magnet toward the 25 nL detection volume and placed right above the microfluidic channel, irradiating the transparent back of the NMR chip. The setup presented here overcomes the limitations of conventional NMR systems for in situ UV–vis illumination, with the microchannel permitting efficient light penetration even in highly concentrated solutions, requiring lower-power light intensities, and enabling high photon flux. The efficacy of the setup is illustrated with two model reactions activated at different wavelengths.